A double jaw connection for elements of an external fixator is known in the art. For example, DE 295 12 917 to Jaquet shows a layered arrangement of two pairs of clamping jaws, which consists of an upper outer clamping jaw and an upper inner clamping jaw, as well as a lower outer clamping jaw and a lower inner clamping jaw. The four clamping jaws are disposed on a central clamping shaft. Between the pairs of clamping jaws, that is, between the two inner clamping jaws, a coil spring is inserted. The coil spring causes the two inner clamping jaws to be pressed apart and pressed against the outer clamping jaws. The clamping jaws are constantly held together with the help of a locking device which acts against the action of the coil spring or elastic means. At the clamping surfaces between each pair of clamping jaws, indentations are provided which form a passage transverse to the clamping shaft for fastening rods or connectors of the external fixator. These passages are open to the outside and enable fastening rods or connectors to be inserted by exerting pressure in the opening of the clamping jaw in the respective passage against the action of the elastic means. After the fastening rods or connectors have snapped into the passages, but prior to the clamping jaws being prevented from articulating with respect to each other, the rods and connectors are held in position by the action of the elastic means.
One disadvantage of this construction is that the coil spring is disposed between the pairs of clamping jaws and, therefore, may not be readily accessible. Moreover, since the spring force depends upon the position of locking device such as a nut, the spring force is not constant. A coil spring is also subject to high fatigue. Therefore, it is desirable to provide an improved device for detachable clamping or fastening elements such as rods, retractors, rings or bone screws. In particular, it is desirable to provide a clamp which allows for independent operation of pairs of clamping jaws, has fewer components than existing devices so that simple operation and cleaning is possible, and has a constant spring force even without actuation of a nut/screw.